1. Field of the Invention
The present invention relates to a testing circuit and a testing method thereof, and more particularly, to a testing circuit and an operation method thereof for a flat panel display.
2. Description of the Related Art
Generally, the means for Flat Panel Display comprises Liquid Crystal Display (LCD), Field Emission Display (FED), Organic Light Emitting Diode (OLED), and Plasma Display Panel (PDP). Since the characteristics of thinness, lightness, flexibility, and compatibility to portable wireless communication and network technologies for present generation and beyond, LCD is undoubtedly the most prevailing flat panel display among all.
Material wise, Thin Film Transistor (TFT) LCD is further classified into at least two categories: amorphous-silicon (a-Si) LCD and poly-silicon (poly-Si) LCD, where Low Temperature Poly-Silicon (LTPS) LCD has been successfully developed. Since LTPS TFT provides higher mobility than a-Si LCD, it serves as an active element of the LCD, and it can be integrated with peripheral circuits onto a glass substrate, i.e., generally known as System on glass (SoG). In testing the flat panel display with conventional testing method, external probe serves to input a digital switching signal to each data line and each scanning line, so as to diagnose each TFT of a pixel.
However, as SoG technique develops, the conventional method becomes ineffective for testing the flat panel display for the data driving circuit has been integrated into the flat panel display. The reason is that on an display panel integrated with data driving circuit, a digital signal feeding the input pin is converted to an analog signal by a Digital-Analog Converter (DAC) as well as by an analog driving circuit, so as to drive the pixels on the panel. Therefore, it is an issue to diagnose the converter circuits on a display panel with data line driving circuit integrated. Furthermore, as the flat panel display is assembled, the external testing probe has no access to the data line and scanning line on the flat panel display, not allowing testing of the performance of the pixels on the flat panel display as succeeding process is completed.